Ayan Mandal According to a recent Harris poll, around 64 percent of Americans believe the soul survives after death. Of course, they would disagree upon the exact nature of the soul, but most will agree that it possesses two central characteristics: one, it is nonmaterial, and two, it allows us to be conscious and make decisions.

It is easy for most to attribute abstract concepts such as thought or decision-making to a nonphysical entity such as the soul. This is because it is very difficult to imagine that these abstractions have a basis in messy cells and tissue. But, if we believe a soul can affect how we behave, at some point it must affect the biological processes that govern how we move our bodies.

This question was considered by late-medieval philosopher René Descartes. Descartes championed a philosophy known as dualism that stressed fundamental differences between physical bodies and nonphysical minds. As I have just pointed out, this philosophy faces a strong problem: How do physical and nonphysical things interact?

Descartes’ answer? The pineal gland. A nut-shaped structure near the center of the brain, the pineal gland is now known to be important for producing melatonin, a hormone that helps regulate sleep patterns. But ancient medics ascribed a greater significance to the gland. It is close to the brain’s ventricles — cavities that contain cerebrospinal fluid keeping the brain moist. But the ancients believed these ventricles contained “psychic pneuma,” an airy substance thought to be an instrument for the soul.

Descartes borrowed this idea from the medics, maintaining that airy animal spirits flowed through the ventricles, controlling movement and sensation. These spirits could both communicate with and be affected by the pineal gland and by the soul. This is how consciousness was explained: It is the result of the body’s sensations communicating with the mind through the bridge of the pineal gland. Free will is also explained as the result of the independent mind sending commands back to the body via the pineal gland bridge.

Yet it does not exactly answer the question, since the interactions between the physical pineal gland and nonmaterial soul still remain a mystery. Furthermore, the pineal gland is actually not located inside the ventricles, as would be necessary for Descartes’ account to be true. Even his contemporaries frowned upon the theory, citing how animals have pineal glands that are just as large as humans, yet their thought processes are not nearly as complex.

Nevertheless, we should not overlook the intellectual courage necessary to take on a problem so difficult. Descartes’ unsatisfying answers just show how one of philosophy’s greatest thinkers could not take this problem down. And the persistence of the problem does not necessarily disprove the existence of a soul. Rather, it forces us to wrestle with the contradictions that our current worldviews may hold.

While the lofty, metaphysical questions considered here may seem unimportant, they potentially color how we approach a number of ethical issues. Many object to physician-assisted suicide based off the premise that human life is fundamentally valuable since persons have souls. For such people, exploring the nature of the soul means to explore what makes life valuable. For atheists, the opposite question persists: If people do not have souls, then what — if anything) — gives life inherent value?

Nobody has a perfectly consistent worldview anyway, yet at the very least, we should be willing to ask ourselves tough questions about our fundamental beliefs. Otherwise, we risk leading lives unexamined, with values unfounded.

Ayan Mandal is a junior in the College. Brain History appears every other Tuesday.